The objective of the Clinical Core is to provide clinical resources for the individual research projects within the Sexually Transmitted Disease Cooperative Research Center. Specifically, the core will 1) identify and recruit research participants for the STD CRC research projects, 2) provide and staff a unique clinical research facility to perform the clinical procedures required for follow-up evaluations, and 3) collect clinical data, conduct physical examinations, and procure research specimens using standardized techniques. The Clinical Core is designed to recruit a population at risk for STDs that is diverse and generalizable. To accomplish this, the Core will include four clinical sites located within a five-minute walk from each other: The Allegheny County Health Department Sexually Transmitted Diseases Clinic, The Magee Womens Hospital Emergency Department and Ambulatory Clinics, The University of Pittsburgh Student Health Services, and The Adolescent Health Center at the Children's Hospital of Pittsburgh. The sites are chosen for three reasons: they serve different segments of the population at risk for STDs, they have previous experience in research project participation , and they each have a STD CRC member in a leadership role. The Clinical Core personnel consists of two physicians, a nurse practitioner and a research assistant, each of whom have worked together previously on STD-related research. This research team will work together to recruit subjects, obtain clinical data and specimens, provide follow-up, and coordinate all clinical aspects of each research project. By using a single research team and a common STD Research Office, the Clinical Core seeks to maximize efficiency and standardization of the clinical procedures to ensure successful clinical procedures for the individual projects.